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screen-printed flexible mri receive coils - flexible polycarbonate sheet

by:Cailong     2019-07-22
screen-printed flexible mri receive coils  -  flexible polycarbonate sheet
Magnetic resonance imaging is an inherent signal. to-noise-
The lack of techniques that limit spatial resolution, diagnose image quality, leads to the fact that the acquisition time of motion artifacts is often very long.
When the receiving coil is uncomfortable due to lack of flexibility or the need to fill in to satisfy the comfort of the patient, this restriction is exacerbated.
Here we report a new method of manufacturing a receiving coil using printing.
Our approach enables highly flexible, extremely lightweight equipment that meets the requirements.
We found that these devices showed similar signals to higher signals. to-
In clinical cases, when the coil can stay away from the body for more than 18mm, the noise ratio is higher than the traditional one.
In addition, we provide detailed analysis of material performance and component performance.
Prototype arrays were integrated for in-vivo research in baby blankets.
This work provides the first fully functional printing coil for 1. 5-and 3-
Clinical scanner
For coils with printing media, the first metal layer of the conductive coil is the screen-
Print to 75 using ASYS APM101 screen printer-μm-
Thick polystyrene film using silver micro
Thin sheet ink purchased from creative materials in a size of 7 μm (118-19A/B).
Before the dielectric material is deposited, the metal layer is annealing for 15 minutes at °c.
Two types of dielectric inks are used when printing tuning and matching capacitors, one is UV-curable resin (
Creative material 116-20)
And an ink.
BT-conductive compound101). A 60-μm-
Thick layers of UV-
Curing Resin for 3-
T coil and cured with mercury arc lamp, the power flux of 3 s is 24 ww cm.
Coil designed for 1. 5-
The T scanner has high requirements for dielectric constants. For these, 30-μm-
The dielectric layer of the capacitor is made of a thick BaTiO ink layer.
After deposition, annealing on the hot plate at 25 °c for 15 minutes.
The top electrode of the capacitor is 30-μm-
Silver micro thick layer-flake ink.
On the heating plate, the finished coil is further annealing for 15 minutes at 25 °c.
For coils with substrate as medium, 75-μm-
Printed thick peeps using a silver micro
Flake ink purchased from Dupont (5064H).
These layers are annealing at 140 °C for 15 min.
The control coil is 70-μm-
75-thick copper etching onμm-
Thick Pyralux AP low-loss substrate.
Advanced technology ceramic 100B lowloss porcelain-
The tuning coil will be formed by welding the capacitor based on the copper line.
Printing Test capacitors are 5mm wide and overlap in length from 1 to 30mm.
The capacitor is mounted with a plastic clip on the copper PCB (
Printed circuit board)
Test the fixture at the 30 × 30mm opening in the plate.
For each measurement, the experimental fixture with the capacitor was tested and calibrated on the Agilent E5061B ENA network analyzer with an open, short and
All coils were tuned using the Phantom used to measure imaging via S11 on The Agilent E5061B ENA network analyzer.
When the matching capacitor sets the impedance, the printed tuning capacitor sets the correct resonance frequency.
By using a different dielectric ink or changing the size of the metal electrode, the capacitance value will vary.
Repeat the optimization process until the coil resonates at the Larmor frequency and displays a 50 Ω impedance.
The coil Q is measured using the Agilent E5061B ENA network analyzer, which has two broadband magnetic field probes, 30 cm apart between them, facing each other to turn | S21 |ref. ).
During all measurements, be careful to ensure that the coil and test equipment are at least 50 cm away from the conductive material to prevent the coil from being artificially loaded.
To measure the loaded Q, the coil is tied to a cubic Phantom with a volume of 7 liters, filled with a solution of 3.
356 u2009 g u2009 l NiCl * 6HO and month.
Month of conductivity of 4 u2009 g u2009 l NaCl.
At 123-127 MHz, 68 kWh Sm SFP.
Unloading Q is measured using the amplitude of the S21 response, averaging 1601 points 16 times, centered on the Larmor frequency, the frequency span of the network analyzer is set to 25 mhz, when Q is loaded, measured with a span of 100 mhz. Single-
The channel cervical spine image is based on the turbo spin echo sequence at 3-
Siemens T scanner with Echo time (TE)
The repeat time is 112 ms (TR)
3500, MS and flip angle (FA)90°.
The field of view is 200 × 200mm, the resolution of the phase encoding and read-out direction is 436 rows, and the slice thickness is 4mm.
To compensate for the change in imaging intensity caused by coil sensitivity, the image is normalized relative to the uniform body coil image.
By placing the coil on the same 7-liter Phantom used to measure the loaded Q, the signal-to-noise ratio measurement is performed on the scanner.
Coil bending tests were performed on different 7-liter Phantom, which contained 3 gg l of CuSO and 3 NaCl g l of NaCl solution.
To connect with the scanner, all coils are clamped into the Test fixture with pins (p-
The diode deactivates the coil during the launch phase of each scan.
This fixture is through half
The long coaxial cable of the wave, the sharp contrast of the interface (
, It holds the pre-amplifier connected to the scanner. The half-
Wavelength coaxial cable containing cable-
Trap circuit tuned to the Larmore frequency.
Image reconstruction does not change with image reconstruction used in traditional coils.
There are two scans used to measure the signal-to-noise ratio
3) 3D gradient echo sequenceSiemens T and 1. 5-
T ge scanner with TE 10 MS, TR 438 MS and FA 25 °.
The field of view is 200 × 200mm with a resolution of 256 phase encoding and reading.
Slice thickness is 5mm.
All experiments use the same prescan settings, reducing changes caused by different magnet flicker, analog gain, and digital gain.
Measure the signal-to-noise ratio of the Phantom image by dividing the signal (
Is the pixel in the Phantom)
, Based on the estimation of noise sd.
Noise is estimated from an image area with no signal, which contains at least 2,800 points and is at least 5 pixels from the edge of the image to avoid the effect of the scanner low levelpass filter.
Noise-only areas do not contain any ringing or stripe artifacts in the phase-coded direction.
In order to maintain the uniform offset of the experiment, a polycarbonate sheet of different thickness was inserted between the mold and each coil. The four-
The channel array is manufactured by printing adjacent coils on the alternating side of the substrate.
The leader of each coil and a PIN diode form a dynamic disable circuit, which is detuned during transmission.
The PIN diode is connected using copper rivets pressed on silver ink marks to form electrical contact.
Use two single coils and connect each to one port of the network analyzer to determine the amount of coil overlap in the array.
The coils overlap until the | S21 | between the coils is minimized.
The array is connected to a low input impedance preamp to take advantage of decoupling with the preamp and reduce cross-over
Channel coupling.
Spinal Anatomy images taken with a printed array use T2-
Weighted spin echo sequence: TE 114.
8 MS, TR 3,500 MS, FA 90 ° and 3-
GE scanner.
Scan Sequence of volunteer knee imaging with printed single knee
Channel coil and four-
Channel array is T2-
The TE sequence parameters are weighted turbo spin echoes of 39 ms, TR 3,000 CUCMS, FA 150 °, and 1 mean.
All experimental procedures were approved by the local ethics committee of the UC Berkeley Committee for the protection of human subjects.
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